The disclosure relates to flap drives such as for example luggage compartment flaps and vehicle doors of a motor vehicle which can be operated electrically.
Flap systems for electric opening and closing are used in motor vehicles in luggage compartment systems or vehicle doors. Triggered by the actuation of an operating element, such as for example a switch, in the passenger compartment of the motor vehicle or by a remote control element, an electric motor is activated so as to open the flap. The electric motor is connected to the respective flap (vehicle door, luggage compartment flap and the like) via a spindle gearing or the like, so as to provide a corresponding speed and force for the opening process.
A closing process can likewise be triggered by means of a corresponding operating element or remote control element or else by pushing the flap in the closing direction. It may furthermore be provided that, in the case of the flap being pushed in the closing direction, the movement of the flap via the corresponding causes a rotation of the electric motor, which thereby produces a generator current. It may be provided that the generator current produced triggers the closing process, such that the electric motor is activated so as to close the flap, and the flap is correspondingly closed.
In general, the exertion of a force on the closing element causes a rotation of the electric motor. If, when a force is exerted on the closing element, a threshold value is exceeded, for example if a user imparts a large force for opening or closing the flap or the flap abuts against an obstruction during a movement driven by the electric motor, a clutch, in particular a slipping clutch, is provided between the electric motor and the gearing which is coupled to the flap, which clutch, when a force greater than a certain magnitude acts (above a disengagement threshold value), is disengaged. The disengagement of the clutch causes the movement of the flap to be decoupled from the movement of the electric motor. In other words, when the clutch in a flap drive is disengaged, the previously positively locking connection between the flap and the electric motor is eliminated.
In the case of electrically driven flap systems, a function is normally realized by means of which a maximum open position of the flap can be programmed by a user. To ensure that the position of the maximum open position is not exceeded, the position of the flap must be known at all times in the control unit which drives the flap system. This is generally possible by detecting the absolute rotor position of the electric motor and assigning this to a flap position. A disengagement of the clutch may however have the result that, in a flap system in which the position of the flap is determined not directly but rather only from the position of the rotor of the electric motor, the position information for the flap is lost. It is therefore necessary to detect the time of the disengagement of the clutch in order to identify when the position information can no longer be used for determining the flap position.
It is an object of the present disclosure to provide a method and a device for detecting a disengagement of a clutch in a flap system.